Remote Sensing in Precision Irrigation

Zhiming YangZhiming Yang

Remote Sensing in Precision Irrigation

Image-based remote sensing Satellite Aircraft

Radar Synthetic Aperture Radar (SAR)

Field-based remote sensing Infrared Thermometer(IRT)

Image-based remote sensing

SatelliteSatellite Thermal scanner (Thermal band)Thermal scanner (Thermal band)

Landsat TM, NOAALandsat TM, NOAA Water stress detection and evaluation of Water stress detection and evaluation of

irrigation system performanceirrigation system performance Evaportranspiration (ET)Evaportranspiration (ET)

Image-based remote sensing

Evapotranspiration in Florida, Feb.29, 1996. Prepared from GOES satellite imagery ( NASA IITA Project. 9/96 )

Image-based remote sensing

Aircraft Thermal scanner Water stress detection E.g. Aircraft-mounted sensors detect water

stress of cotton in central California

Image-based remote sensing

E.g. A thermal image of a cotton canopy from a helicopter

Image-based remote sensing

Limitations SatelliteSatellite Thermal band temporal resolution resolution

Landsat TM 60 m 16 days NOAA 1100 m 0.5 days

AircraftHigh costDifficult for geometric correction

SAR

AdvantageSAR sensors are sensitive to soil moisture

and can be used to directly measure soil moisture

DisadvantageData requires extensive use of processing to

remove surface induced noise such as soil surface roughness, vegetation.

Field-based remote sensing

Advantages High resolution Being able to control monitoring conditions Easy to quantify measurement results

Disadvantage Difficult for large area

Infrared thermometer Easy and convenient to use

Infrared thermometer

                             

Precision Irrigation by IRT

Where and when to irrigate Temperature and time threshold Crop water stress index (CWSI)

How much to irrigate Evaportranspiration Crop water requirement

Infrared thermometer

Temperature and time threshold

Temperature threshold(To) A biologically determined optimum

temperature for each crop Time threshold (TT)

A specific quantity of time when canopy temperature is above the To

Temperature and time threshold

Irrigate where and when crop is warmer than temperature threshold and it lasts longer than time threshold in a day

Temperature threshold – crop-specific

Cotton and corn 82 0 F, Soybean 84 0 F Time threshold - location-specific(eg.Cotton)

 Locations Lubbock, TX Shafter, CA Missipipi State, MS

Threshold time(hour) 4.6 6.8 6.9

Crop water stress index (CWSI)

Many methods to calculate CWSI

CWSI =   TC = canopy temperature

TCi = Sensed for irrigation

TCmin = non-watered stressed and calculate from solar radiation and humidity readings or measured in a well-watered plot

TCmax = “completely” water stressed and calculate from air temperature and solar radiation

 

minTCmaxTC

minTC

iTC

CWSI

Irrigate for sensitive crops where and when CWSI is between 0.2 and 0.5

Irrigate for drought-tolerant crops where and when CWSI is between 0.5 and 0.7

E.g., corn could go as high as 0.4 on the crop water stress index and still produce a harvest, whereas cotton has a much lower stress threshold

How much to irrigate

Evaportranspiration(ET) Integrate IRT data, weather station data and ET

model to calculate ET Crop water requirements

SoftwareIWR(Silsoe College)KANSCHED (K-state Research and

Extension)IRT-Etc(Center for irrigation technology)

PI Example II

Location: Florence, SC Irrigation Systems: self-propelled center-pivot

irrigation systems Research team: Carl Ro Camp, Eo John Sadler

and etc, Coastal Plains Soil, Water, and Plant Research Center, USDA-ARS

PI Example II

PI Example II

ObjectiveObjective

To manage water and chemical applications to small areas within the total irrigation system area based on stored data, real- time plant and soil measurements, or a combination of the two on Coastal Plain soils

PI Example II

MethodsMethods Modify two commercial center pivot irrigation Modify two commercial center pivot irrigation

systems with computer-aided managementsystems with computer-aided management The system The system is controlled by a computer using is controlled by a computer using

specialized software and soil, crop, and cultural specialized software and soil, crop, and cultural information stored in a database to control information stored in a database to control all water and nutrient applications all water and nutrient applications

PI Example II

Infrared Infrared thermometers are mounted on top of thermometers are mounted on top of the vertical masts at right end of horizontal the vertical masts at right end of horizontal tubes to measure crop water stress. The tubes to measure crop water stress. The modified application system has been used to modified application system has been used to apply water and nitrogen to a field experiment apply water and nitrogen to a field experiment with fixed, regular plot boundarieswith fixed, regular plot boundaries

Current work includes improvements to make Current work includes improvements to make the system more reliable and to accommodate the system more reliable and to accommodate irregular-shaped areas of variation. irregular-shaped areas of variation.

Limitations

IRT method is applicable only to mature plants with a well-developed canopy. It is not applicable to calculations of bare soil evaporation

Misleading Sharp climatic changes may cause low canopy

temperatures even when soil water is limited; Alternatively, under such conditions, high canopy temperatures may be observed when soil water is not limiting

Some other stresses such as pest infestation can also rising of canopy temperature

PI Example II

Any Questions

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